SARS explained

Scientists now say SARS is killing one in five people
who contract the virus, and health officials have just confirmed the first case
in the UK – so what is it and should we be worried?

A new strain

The SARS virus is a new strain of the coronavirus family. It
is not thought to be as contagious as influenza.

The first cases of severe acute respiratory syndrome (SARS)
emerged in November 2002 and originated in southern China. The number quickly
multiplied and the virus soon spread to other parts of the world, largely
through air travel.

But how did it appear so suddenly? Dr Valerie Delpech,
communicable disease consultant with the Health Protection Agency (HPA), says:
'It's difficult to know exactly what makes a disease become virulent in
humans…there's a theory about having close contact with animals and changes in
the environment that make it acceptable for the virus to travel between
species.'

Through an international collaboration between health
organisations, such as the HPA and the World Health Organisation (WHO),
scientists from the US and Hong Kong have quickly identified that SARS is a
result of a completely new strain of the coronavirus family.

According to Dr Delpech, coronaviruses (which also affect birds
and pigs) are responsible for the common cold, respiratory tract infections,
and 'gastroenteritis-type illness' in humans.

Going global

WHO figures show that since SARS was first detected there have
been more than 7,500 cases and nearly 600 deaths globally.

Although the disease first struck in November last year it
wasn't until February 2003 that the Chinese Ministry of Health raised the
alarm. In March, the WHO confirmed that SARS was a worldwide health threat and
advised against travel to the worst-affected areas. These included Canada,
Indonesia, Singapore, Thailand, and Vietnam. Since then, areas of China,
Taiwan, and Hong Kong have been added to this list.

The statistics seem to suggest SARS must be highly contagious,
but Dr Delpech stresses that this is not the case. 'It's probably less
infectious than influenza [flu],' she says. Nevertheless, she admits it is
spread through close contact.

Despite this, Dr Delpech says there is little need for people to
wear face masks on flights or walking down the street. 'Unless you're coming
into close contact with the person for a considerable time, you're really not
at risk.'

She adds that most cases have been in family members and
healthcare workers who have been exposed to SARS patients.

Dr Delpech's advice is to avoid areas where the virus has been
detected, including hospitals treating SARS patients, to maintain a good level
of hygiene, including handwashing, and to recognise the symptoms so you can be
treated quickly.

Spotting symptoms

The number of probable SARS cases in the UK varies daily as new
cases are reported and others are discounted. So far 159 suspected cases of
SARS have been reported to the HPA communicable disease surveillance
centre.

Dr Maria Zambon, head of the HPA respiratory virus unit, says,
'Since reporting began, a total of eight people have been classified as a
probable SARS case at one time or another.' At the moment there are three
probable cases, and one confirmed.

A recent study in the British Medical
Journal found the disease was more likely to prove fatal for older
people and those with conditions such as asthma and diabetes. That the virus
can be life threatening highlights the need for early treatment; the WHO and
the HPA have issued guidelines on how to recognise symptoms.

The main signs of infection are fever (38°C), headache, muscle
pain, and one or more respiratory symptoms such as a cough or shortness of
breath. Dr Delpech adds the symptoms are a bit like flu at first, but develop
quite quickly over a few days into a chest infection, making breathing more
difficult.

Dr Delpech also points out that if you have come into contact
with the SARS virus you will develop symptoms within 10 days of exposure. She
confirms that if symptoms have not developed by then, there is very little
chance that SARS will develop at all.

Containing the virus

To ensure that all cases of SARS are detected quickly, the WHO
has issued advice to affected areas on how to screen travellers at airports for
signs of the virus. For cases that slip through the net, the HPA and Department
of Health have established surveillance systems in the UK.

People who have recently visited a SARS-affected area and have
developed SARS-like symptoms within 10 days of their return are advised to stay
at home and ring NHS Direct on 0845 4647 or call their GP. Dr Delpech confirms
they will then be assessed and may be asked to go to their local surgery,
accident and emergency department, or their GP will come out and visit them.

Dr Delpech says: 'The majority of people…have turned out not to
have SARS, but every precaution is taken to make sure that every patient is
adequately treated and isolated, and that there are adequate infection control
procedures both within the household, general practice or in the hospital
setting.'

New treatments needed

Researchers writing in The Lancet have
found there may be a chance that the SARS virus will mutate into a more harmful
form, increasing the need for vaccines and improved treatments. However,
scientists have suggested that such treatments may be possible and that some
existing drugs could be modified to combat the coronavirus.

Experts are confident that new drugs can be developed now that
the structure of a substance vital to the survival of the virus, known as main
proteinase, has been discovered.

Despite the resilience of the SARS virus, the number of new
cases appears to be falling. So, for those who feared a global epidemic, it
seems the danger may have passed. As Dr Delpech says, there's no need to panic.
The disease is under control in most areas of the world and, with only one
confirmed case, has hardly touched the UK.

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